Datele problemei:
msol1 = 400g, c1 = 10%
md = 20g
c2=?
========================
c1=md1*100/msol1 => md1 = c1*msol1/100 = 10*400/100 = 40g
c2 = md2*100/msol2 = (md+md1)*100/(msol1+md) = (20+40)*100/(400+20) =
60*100/420 = 14,28%
Concentratia solutiei creste.